Glossary of biology
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Any non-living chemical or physical part of the environment that affects living and the functioning of , such as the atmosphere and water resources.
The shedding of flowers, leaves, and/or fruit following formation of scar tissue in a plant.
A process in which one substance permeates another. A fluid permeates or is dissolved by a liquid or solid. Skin absorption is a route by which substances can enter the body through the skin.
The spectrum of electromagnetic radiation that has passed through a medium which absorbs radiation of certain wavelengths.
to a new climate, as with a new temperature or altitude or environment.
A molecule that participates in many reactions in , , and , notably the .
A type of , such as a flatworm or a jellyfish, with a body plan that lacks a fluid-filled between the body wall and the digestive tract. Rather, semi-solid mesodermal tissues between the gut and body wall hold the animal's in place. Contrast and .
The local change in voltage that occurs when the membrane potential of a specific location along the of a rapidly depolarizes, such as when a nerve impulse is transmitted between .
The energy that an atomic system must acquire before a process (such as an emission or reaction) can occur.
The part of an or antibody at which molecules bind and undergo a chemical reaction.
Transport of a substance (such as a protein or ) across a against a concentration gradient. Unlike , active transport requires an expenditure of energy.
The process by which organisms diversify rapidly from an ancestral into a multitude of new forms, particularly when a change in the makes new resources available, creates new challenges, or opens new .
A purine-derived organic compound which is one of the four canonical nucleobases used in the and . Its derivatives are involved in a wide variety of reactions, including .
adenosine triphosphate (ATP)
An organic compound derived from that functions as the major source of energy for chemical reactions inside living . It is found in all forms of life and is often referred to as the "molecular currency" of intracellular energy transfer.
A type of loose connective tissue made of mostly adipocytes and found in human and animal , where it is colloquially known as body fat.
Capable of surviving and growing in the presence of oxygen.
The study of organic particles which are passively transported by the air, including , fungal spores, very small insects, pollen grains, and .
The practice of cultivating land, growing food, and/or raising livestock.
The study of plant nutrition and growth, especially as a way to increase crop yield.
Any member of a diverse group of , , mostly aquatic organisms ranging from simple microalgae to massive or forms such as kelp. Algae may reproduce or , and are often compared to , though they lack most of the complex cell and tissue types that characterize true plants.
A form of which occurs when biological of the same become isolated from each other to an extent that prevents or interferes with genetic interchange.
A class of organic compounds containing an amine group and a carboxylic acid group which function as the fundamental building blocks of and play important roles in many other biochemical processes.
An organism which produces an egg composed of a shell and membranes that creates a protected environment in which the can develop out of water.
A set of structures in different organisms which have similar form or function but were not present in the organisms' . The cladistic term for the same phenomenon is homoplasy.
The branch of biology that studies the structure and of living organisms and their various parts.
Any member of a of organisms belonging to the Animalia. With few exceptions, animals , , are , , and grow from a blastula during embryonic development. An estimated 7 million distinct animal currently exist.
A type of antimicrobial used in the treatment and prevention of .
The scientific study of spiders, scorpions, pseudoscorpions, and harvestmen, collectively called arachnids.
The process by which humans use animal breeding and plant breeding to control the development of particular in organisms by choosing which individual organisms will and create . While the deliberate exploitation of knowledge about and in the hope of producing desirable characteristics is widely practiced in and experimental biology, artificial selection may also be unintentional and may produce unintended (desirable or undesirable) results.
A type of involving a single parent that results in that are genetically identical to the parent.
The branch of biology concerned with the effects of outer space on living organisms and the search for extraterrestrial life.
The system of responses of an organism directed against its own healthy cells and tissues.
An organism capable of producing complex organic compounds from simple substances present in its surroundings, generally by using energy from sunlight (as in ) or from inorganic chemical reactions (as in ). Autotrophs do not need to consume another living organism in order to obtain energy or organic carbon, as opposed to .
A type of lymphocyte in the humoral immunity of the adaptive immune system.
An enormous and diverse clade of microscopic, , single-celled organisms which lack a true . They represent one of the three fundamental biological .
A that infects and multiplies within .
The inactive X chromosome in a female somatic cell, rendered inactive in a process called lyonization, in those species in which sex is determined by the presence of the Y (including humans) or W chromosome rather than the diploidy of the X or Z.
An organelle formed from a centriole, and a short cylindrical array of microtubules. Also called a basal granule, a kinetosome, and in older cytological literature, a blepharoplast.
The study of the evolutionary basis for animal behavior due to ecological pressures.
A dark green to yellowish-brown fluid, produced by the liver of most vertebrates, which aids the digestion of lipids in the small intestine. Also called gall.
The process by which one prokaryotic cell divides into two identical daughter cells.
A formal system of classifying of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages.
The process of catalysis in biological systems. In biocatalytic processes, natural catalysts, such as protein enzymes, perform chemical transformations on organic compounds.
The branch of biology that studies the chemical properties, compositions, reactions, and processes related to living organisms.
A contraction of "biological diversity" generally referring to the variety and variability of life on Earth.
The application of concepts and methods of biology to solve real-world problems related to the life sciences or the application thereof.
The study of the transformation of energy in living organisms.
The study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area.
The application of computer technology to the management of biological information.
The hierarchy of complex biological structures and systems, designed to define life through a reductionist approach.
The study of life and living .
Organic matter derived from living or recently living organisms. Biomass can be used as a source of energy and it most often refers to plants or plant-based materials which are not used for food or feed, and are specifically called lignocellulosic biomass.
The theoretical use of mathematical models and abstractions of living systems to understand and predict biological problems.
Any very large area on the Earth's surface containing fauna and flora (animals and plants) adapting to their environment. Biomes are often defined by such as climate, topographical relief, geology, soils, and water resources.
The study of the structure and function of biological systems by means of the methods of "mechanics", which is the branch of physics involving analysis of the actions of forces.
The application of engineering principles and design concepts to medicine and biology for healthcare purposes (e.g. diagnostic or therapeutic).
The pursuit of answers to medical questions. These investigations lead to discoveries, which in turn lead to the development of new preventions, therapies, and cures for problems in human and veterinary health. Biomedical research generally takes two forms: basic science and applied research.
Molecules and ions that are present in organisms, essential to some typically biological process such as , morphogenesis, or development.
The application of approaches traditionally employed in physics to study biological systems.
Biotechnology is the use of living systems and organisms to develop or make products, or "any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use" (UN Convention on Biological Diversity).
A form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs.
A mammalian blastula in which some differentiation of cells has occurred.
A body fluid that circulates in humans and other vertebrate animals and is generally responsible for delivering necessary substances such as oxygen and nutrients between the cells and tissues of the body and transporting metabolic waste products away from those same cells and tissues.
A semipermeable membrane separating the blood from the cerebrospinal fluid, and constituting a barrier to the passage of cells, particles, and large molecules.
The branch of biology that studies .
A science that leads to natural healthy ecological homes, schools, and workplaces that exist in harmony with the environment.
The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis are the chemical reactions that convert carbon dioxide and other compounds into glucose. These reactions occur in the stroma, the fluid-filled area of a chloroplast outside the thylakoid membranes. These reactions take the products (ATP and NADPH) of light-dependent reactions and perform further chemical processes on them. There are three phases to the light-independent reactions, collectively called the Calvin cycle: carbon fixation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP) regeneration.
The conversion process of inorganic carbon (carbon dioxide) to organic compounds by living organisms.
Any member of two classes of chemical compounds derived from carbonic acid or carbon dioxide.
One of a class of organic pigments produced by and , as well as certain and .
An found in nearly all living organisms exposed to oxygen, including bacteria, plants, and animals.
The basic structural and functional unit of all living , and the smallest functional unit of life. A cell may exist as an independent, self-replicating unit (as in the case of ), or in cooperation with other cells, each of which may be specialized for carrying out particular functions within a larger . Cells consist of enclosed within a and sometimes a , and serve the fundamental purpose of separating the controlled environment in which biochemical processes take place from the outside world. Most cells are visible only under a microscope.
The branch of biology that studies the structure and function of living , including their properties, processes, chemical composition, , the they contain, and their interactions with their environment. This is done at both microscopic and levels.
Any process by which a parent divides into two or more daughter cells. Examples include , , and .
The semipermeable surrounding the of a .
The "control room" for the cell. The nucleus gives out all the orders.
Grown in the cell's center, it fuses with the parental plasma membrane, creating a new cell wall that enables cell division.
The theory that all living things are made up of cells.
A tough, often rigid structural barrier surrounding certain types of (such as in , , and most ) that is immediately external to the .
Of or relating to a .
central dogma of molecular biology
A framework for understanding the movement of genetic information between information-carrying biopolymers within biological systems. Popularly (though simplistically) stated as " makes and RNA makes ", the principle attempts to capture the notion that the transfer of genetic information only naturally occurs between certain classes of molecules and in certain directions.
A cylindrical cell structure composed mainly of a protein called tubulin that is found in most eukaryotic cells.
An organelle that is the main place where cell microtubules get organized, occurring only in plant and animal cells and regulating the cell division cycle.
A chemical substance consisting of two or more different chemically bonded elements, with a fixed ratio determining the composition. The ratio of each element is usually expressed by a chemical formula.
The state in which both reactants and products are present in concentrations which have no further tendency to change with time in a chemical reaction.
A process that leads to the transformation of one set of chemical substances to another.
A branch of the physical sciences that studies the composition, structure, properties, and change of matter. Chemical interactions underlie all biological processes.
Any of several pigments found in cyanobacteria, algae, or .
Organelles, specialized subunits, in plant and algal cells, main role of which is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight and converts and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water.
An organic molecule, a sterol, a type of lipid molecule, and biosynthesized by all animal cells because it is an essential structural component of all animal cell membranes—essential to maintain both membrane structural integrity and fluidity.
A threadlike strand of in the cell nucleus that carries the genes in a linear order.
citric acid cycle
A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of guanosine triphosphate (GTP). In addition, the cycle provides precursors of certain amino acids as well as the reducing agent NADH that is used in numerous other biochemical reactions. Its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular metabolism and may have originated abiogenically.
Clonal selection theory is a scientific theory in immunology that explains the functions of cells (lymphocytes) of the immune system in response to specific antigens invading the body. The theory has become the widely accepted model for how the immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens.
The process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually.
The scientific study of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions.
The independent development of similar characteristics in of different lineages.
A mechanism that happens in nature and is mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other.
A fold in the inner membrane of a .
The branch of biology that studies the effects of low temperatures on living things within Earth's cryosphere or in laboratory experiments.
All of the material within a and enclosed by the , except for the . The cytoplasm consists mainly of water, the gel-like cytosol, various , and free-floating granules of and other .
One of the four main nucleotide bases found in DNA and RNA, along with adenine, guanine, thymine, and uracil (in RNA); it is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at position 2).
A cytoskeleton is present in the of all , including bacteria, and archaea. It is a complex, dynamic network of interlinking protein filaments that extends from the cell nucleus to the cell membrane. The cytoskeletal systems of different organisms are composed of similar proteins. In eukaryotes, the cytoskeletal matrix is a dynamic structure composed of three main proteins, which are capable of rapid growth or disassembly dependent on the cell's requirements.
The genetic contribution of an individual to the next generation's gene pool relative to the average for the population, usually measured by the number of offspring or close kin that survive to reproductive age.
Deciduous means "falling off at maturity" or "tending to fall off", and it is typically used in order to refer to trees or shrubs that lose their leaves seasonally (most commonly during autumn) and to the shedding of other plant structures such as petals after flowering or fruit when ripe.
A chemical reaction that involves the loss of a water molecule from the reacting molecule.
A process in which proteins or nucleic acids lose the quaternary, tertiary and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, or an organic solvent.
A short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.
A microbially facilitated process of nitrate reduction (performed by a large group of heterotrophic facultative anaerobic bacteria) that may ultimately produce molecular nitrogen (N2) through a series of intermediate gaseous nitrogen oxide products. Part of the nitrogen cycle.
deoxyribonucleic acid (DNA)
A that serves as the fundamental hereditary material in all living organisms. A set of four bases is used in the nucleotide sequences which comprise each DNA molecule: (abbreviated A), (C), (G), and (T); these four bases are individually attached to a sugar-phosphate complex to form a complete nucleotide.
The process of reversing the charge across a (such as that of a neuron), thereby causing an . In depolarization, the inside of the membrane, which is normally negatively charged, becomes positive and the outside becomes negative. This is brought about by positive sodium ions rapidly passing into the axon.
A cell structure specialized for cell-to-cell adhesion.
The branch of biology that studies the processes by which living organisms grow and develop over time. The field may also encompass the study of , , , and the growth and differentiation of in mature tissues.
The replication of a molecule; the process of producing two identical copies from one original DNA molecule, in which the double helix is unwound and each strand acts as a template for the next strand; nucleotide bases are matched to synthesize the new partner strands.
The process of determining the precise order of nucleotides within a molecule.
A motor protein (also called molecular motor or motor molecule) in cells which converts the chemical energy contained in ATP into the mechanical energy of movement.
The efficiency with which energy is transferred from one trophic level to the next. It is determined by a combination of efficiencies relating to organismic resource acquisition and assimilation in an . Primary production occurs in organisms of an ecosystem.
An ecological pyramid (also trophic pyramid, eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem. Biomass is the amount of living or organic matter present in an organism.
The more or less predictable and orderly set of changes that occurs in the composition or structure of an ecological community over time.
The scientific analysis and study of interactions between and their . It is an interdisciplinary field that includes biology, geography, and Earth science.
A biological discipline that studies the adaptation of an organism's physiology to environmental conditions.
A community of living in conjunction with the of their physical environment, interacting as a system.
In evolutionary ecology, a genetically distinct geographic variety, , or race within a which is adapted to specific environmental conditions.
The outermost layer of cells or tissue of an in early development, or the parts derived from this, which include the epidermis, nerve tissue, and nephridia.
An organism in which internal physiological sources of heat are of relatively small or quite negligible importance in controlling body temperature. Colloquially, these organisms often referred to as "cold-blooded".
A small molecule that selectively binds to a and regulates its biological activity. In this manner, effector molecules act as ligands that can increase or decrease enzyme activity, gene expression, or cell signaling.
Conducted or conducting outwards or away from something (for nerves, the central nervous system; for blood vessels, the organ supplied). Contrast .
The organic vessel containing the in which an animal develops until it can survive on its own, at which point the developing organism emerges from the egg in a process known as hatching.
A gradient of electrochemical potential, usually for an that can move across a membrane. The gradient consists of two parts: the electrical potential and the difference in chemical concentration across the membrane.
The range of all possible frequencies of electromagnetic radiation. When referring to an object, the electromagnetic spectrum is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.
A negatively charged subatomic particle, symbolized by e− or β−.
An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. It is an oxidizing agent that, by virtue of its accepting electrons, is itself reduced in the process.
electron carrier. Any of various molecules that are capable of accepting one or two electrons from one molecule and donating them to another in the process of electron transport. As the electrons are transferred from one electron carrier to another, their energy level decreases, and energy is released.
An electron donor is a chemical entity that donates electrons to another compound. It is a reducing agent that, by virtue of its donating electrons, is itself oxidized in the process.
The electron microscope is a type of microscope that uses a beam of electrons to create an image of the specimen. It is capable of much higher magnifications and has a greater resolving power than a light microscope, allowing it to see much smaller objects in finer detail.
electron transport chain
The site in a mitochondrion of oxidative phosphorylation in eukaryotes. The NADH and succinate generated by the citric acid cycle are oxidized, providing energy to power ATP synthase. Photosynthetic electron transport chain of the thylakoid membrane.
A developing stage of a .
The branch of biology that studies the development of (sex cells), fertilization, and development of and . Additionally, embryology involves the study of congenital disorders that occur before birth.
Endangered species are threatened by factors such as habitat loss, hunting, disease and climate change, and usually, endangered species, have a declining population or a very limited range.
The ecological state of an organism or species being unique to a defined geographic location, such as an island, nation, country, habitat type, or other defined zone. Organisms are said to be endemic to a place if they are indigenous to it and found nowhere else.
A type of chemical reaction in which the standard change in free energy is positive, and energy is absorbed.
A gland of the animalian endocrine system that secretes directly into the rather than through a duct. In humans, the major glands of the endocrine system include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, hypothalamus, and adrenal glands.
The collection of that produce which regulate , growth and development, tissue function, and a wide variety of other biological processes.
A form of in which a cell transports molecules such as proteins into the cell's interior by engulfing them in an energy-consuming process.
One of the three primary germ layers in the very early human . The other two layers are the (outside layer) and (middle layer), with the endoderm being the innermost layer.
A type of organelle found in eukaryotic cells that forms an interconnected network of flattened, membrane-enclosed sacs or tube-like structures known as cisternae.
The tissue produced inside the seeds of most of the flowering plants following fertilization.
An evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms, first articulated in 1905 and 1910 by the Russian botanist Konstantin Mereschkowski, and advanced and substantiated with microbiological evidence by Lynn Margulis in 1967.
An organism that maintains its body at a metabolically favorable temperature, largely by the use of heat set free by its internal bodily functions instead of relying almost purely on ambient heat.
Entomology is the study of insects, but etymology is the study of words.
the branch of biology concerned with the relations between organisms and their environment. bionomics, ecology. biological science, biology - the science that studies living organisms. palaeoecology, paleoecology - the branch of ecology that studies ancient ecology.
Enzymes are biological molecules (proteins) that act as catalysts and help complex reactions occur everywhere in life. Let's say you ate a piece of meat. Proteases would go to work and help break down the peptide bonds between the amino acids.
Epidemiology is the study and analysis of the patterns, causes, and effects of health and disease conditions in defined populations. It is the cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare.
A sub-field of that studies cellular and physiological phenotypic trait variations caused by external or environmental factors which affect how cells express , as opposed to those caused by changes in the sequence.
An organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, marine environments or from debris accumulating around it.
The primary female sex .
The scientific study of non-human animal behaviour (i.e. excluding human behaviour) and usually with a focus on behaviour under natural conditions, and viewing behaviour as an evolutionarily adaptive trait.
Organisms whose cells have a nucleus enclosed within membranes, unlike Prokaryotes (Bacteria and other Archaea).
The change in the characteristics of of biological organisms over successive , which may occur by mutation, gene flow, , or random chance.
Evolutionary biology is the subfield of biology that studies the evolutionary processes that produced the diversity of life on Earth starting from a single origin of life. These processes include the descent of species, and the origin of new species.
A form of active transport and bulk transport in which a cell transports molecules out of the cell by expelling them through an energy-dependent process.
It is exhibited when the rate of change of the value of a mathematical function is proportional to the function's current value, resulting in its value at any time being an exponential function of time.
A type of in which a unites with an external to the body or bodies of the parent organisms. Contrast .
Of or occurring in the space outside the of a . Contrast .
A transmission of genes that take place outside the nucleus.
An organism which is capable of producing energy through aerobic respiration and then switching to anaerobic respiration depending on the amounts of oxygen and fermentable material in the environment.
A process that consumes sugar in the absence of oxygen.
An animal after eight weeks of development.
A lash-like appendage that protrudes from the body of certain bacterial and eukaryotic cells.
flavin adenine dinucleotide (FAD)
A redox cofactor, more specifically a prosthetic group of a protein, involved in different important enzymatic reactions in .
The chain of eating and getting nutrition which starts from a small herbivores animal and ends up at a big carnivorous organism.
A loss of genetic variation that takes places when a new population is established by a very small number of individuals from a larger population.
A family of that act as molecular switches inside , and are implicated in transmitting signals from a diversity of stimuli outside a cell to its interior.
Any segment of that contains the information necessary to produce a functional and/or product in a controlled manner. Genes are often considered the fundamental molecular units of . The transmission of genes from a parent cell or organism to its is the basis of the inheritance of .
A set of all genes, or genetic information, in any population, usually of a particular .
A set of rules used by living to translate information encoded within genetic material (DNA or mRNA sequences) into proteins.
An alteration in the frequency of an existing gene variant in a population due to random sampling of organisms.
Variations of genomes between members of species, or between groups of species thriving in different parts of the world as a result of genetic mutation. Genetic diversity in a population or species is a result of new gene combinations (e.g. crossing over of chromosomes), genetic mutations, genetic drift, etc.
The study of heredity.
The entire set of genetic material contained within the of an organism, , or .
Part of the genetic makeup of a , and therefore of an organism or individual, which determines one of its characteristics (phenotype).
An organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, and dinosaurs, including birds), earthworms, some gastropods, some fish, and some crustaceans.
One of the four main nucleobases found in the nucleic acids and , the others being adenine, cytosine, and thymine (uracil in RNA).
A place for animals, people, and plants and non-living things.
A form of learning in which an organism decreases or desists its responses to a stimulus after repeated or prolonged presentations .
The passing on of from parents to their , either through or . Offspring cells and organisms are said to inherit the genetic information of their parents.
A sexually reproducing organism with both male and female reproductive organs.
The branch of that studies reptiles and amphibians.
The improved or increased function of any biological quality in a .
The study of the microscopic anatomy of cells and tissues of plants and animals.
Any member of a class of signaling molecules produced by glands in organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.
Any living organism that harbors another living organism (known as a "guest" or ), whether the guest is , mutualistic, or commensalist in its interactions with the host. The guest typically receives shelter and nourishment from the host.
An organic compound consisting entirely of hydrogen and carbon atoms. Hydrocarbons from which one hydrogen atom has been removed are functional groups called hydrocarbyls.
The branch of biology devoted to the study of fish, including bony fishes (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha).
The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful.
Glycoprotein molecules produced by plasma cells (white blood cells) which act as a critical part of the immune response by specifically recognizing and binding to particular antigens, such as bacteria or viruses, and aiding in their destruction. Also known as antibodies.
The invasion of an organism's cells or tissues by a -causing , its growth and/or multiplication, and the reaction of the organism to the infectious agent and the it produces. The variety of biological pathogens capable of causing infections includes certain , , , , parasitic worms, and arthropods.
Insulin helps keeps your blood sugar level from getting too high (hyperglycemia) or too low (hypoglycemia). ... After you eat food and your blood sugar level rises, cells in your pancreas (known as beta cells) are signaled to release insulin into your bloodstream.
The various forms of cross-disciplinary and multitaxon research.
A group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumor cells. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their antiviral defenses.
A type of which takes place inside the -producing individual.
International System of Units
(French: Système international d'unités; abbreviated SI) The modern form of the metric system, and the most widely used system of measurement.
Of or occurring inside or within the enclosed interior of a . Contrast .
A group of animals that have no backbone, unlike animals such as reptiles, amphibians, fish, birds and mammals, which all have a backbone.
An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
The complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion.
A molecule with the same chemical formula as another molecule, but with a different chemical structure. That is, isomers contain the same number of atoms of each element, but have different arrangements of their atoms.
Refers to two solutions having the same osmotic pressure across a semipermeable membrane. This state allows for the free movement of water across the membrane without changing the concentration of solutes on either side.
The midsection of the small intestine of many higher vertebrates like mammals, birds, and reptiles. It is present between the duodenum and the ileum.
An that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.
A distinct juvenile form many undergo before into adults. Animals with indirect development, such as insects, amphibians, or cnidarians, typically have a larval phase of their .
Law of Independent Assortment
The principle, originally formulated by Gregor Mendel, stating that when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.
A colourless cell which circulates in the blood and body fluids and is involved in counteracting foreign substances and disease; sometimes called a white blood cell. There are several types, all amoeboid cells with a nucleus, including lymphocytes, granulocytes, and monocytes.
The fibrous connective tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.
Any set of one or more which are sufficiently close together on the same chromosome that they are very unlikely to assort independently and therefore are usually inherited together.
A substance that is insoluble in water and soluble in alcohol, ether, and chloroform. Lipids are an important component of living cells. Together with carbohydrates and proteins, lipids are the main constituents of plant and animal cells. Cholesterol and triglycerides are lipids.
A biochemical assembly that contains both proteins and lipids, bound to the proteins, which allow fats to move through the water inside and outside cells. The proteins serve to emulsify the lipid molecules.
Mitosis and cytokinesis together define the mitotic (M) phase of an animal cell cycle – the division of the mother cell into two daughter cells, genetically identical to each other and to their parent cell.
Evolution on a scale of separated gene pools. Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution, which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.
A very large molecule, such as a protein, commonly created by polymerization of smaller subunits (monomers). They are typically composed of thousands or more atoms.
Nutrients needed in large amounts which provide calories or energy. Nutrients are substances needed for growth, metabolism, and for other body functions. There are three basic types of macronutrients: fats, proteins, and carbohydrates.
A kind of swallowing cell, which means it functions by literally swallowing up other particles or smaller cells. Macrophages engulf and digest debris (like dead cells) and foreign particles through the process of phagocytosis, so macrophages act like scavengers.
The study of mammals, a class of vertebrates with characteristics such as homeothermic metabolism, fur, four-chambered hearts, and complex nervous systems.
The study of organisms in the ocean or other marine bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather than on taxonomy.
A cell filled with basophil granules, found in numbers in connective tissue and releasing histamine and other substances during inflammatory and allergic reactions.
The continuation of the spinal cord within the skull, forming the lowest part of the brainstem and containing control centres for the heart and lungs.
A specialized type of in which a dividing parent cell proceeds through two consecutive divisions, ultimately producing four genetically unique daughter cells in each of which the number is half of that in the original parent cell. This process is exclusive to cells of the sex organs in , where it serves the purpose of generating such as , , or .
When a nerve or muscle cell is at "rest", its membrane potential is called the resting membrane potential. In a typical neuron, this is about –70 millivolts (mV). The minus sign indicates that the inside of the cell is negative with respect to the surrounding extracellular fluid.
A large family of RNA molecules that convey genetic information from DNA to the ribosome.
The third phase of mitosis, in which duplicated genetic material carried in the nucleus of a parent cell is separated into two identical daughter cells. During metaphase, the cell's chromosomes align themselves in the middle of the cell through a type of cellular "tug of war".
The study of microscopic organisms, such as bacteria, viruses, archaea, fungi and protozoa. This discipline includes fundamental research on the biochemistry, physiology, cell biology, ecology, evolution and clinical aspects of microorganisms, including the host response to these agents.
The alteration in allele frequencies that occurs over time within a population.
In , the part of the during which the division of the takes place and duplicated are separated into two distinct nuclei. Mitosis is generally preceded by the "S" stage of , when the cell's is , and followed by , when the and are divided into two new daughter cells. It is similar to but distinct from and .
The smallest particle in a chemical element or compound that has the chemical properties of that element or compound. Molecules are made up of atoms that are held together by chemical bonds. These bonds form as a result of the sharing or exchange of electrons among atoms.
The branch of biology concerning biological activity at the molecular level. The field of molecular biology overlaps with biology and chemistry and in particular with genetics and biochemistry.
A molecule that can be reversibly changed between two or more stable states.
A molecule that "can undergo polymerization thereby contributing constitutional units to the essential structure of a macromolecule".
A neuron whose cell body is situated in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly control effector organs, mainly muscles and glands.
A membrane that lines various cavities in the body and covers the surface of internal organs.
Having or consisting of more than one , as opposed to being .
The branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicine, food, and entheogens, as well as their dangers, such as poisoning or infection.
A basic rod-like unit of a muscle .
A superfamily of motor best known for their roles in muscle contraction and in a wide range of other processes in eukaryotes.
A process in nature in which organisms possessing certain characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations.
The scientific study of the nervous system.
An electrically excitable cell that receives, processes, and transmits information through electrical and chemical signals.
An compound that enable neurotransmission.
The role and position an organism or taxon fills within its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. A species' niche includes all of its interactions with the biotic and abiotic factors of its environment.
The biopolymers, or small biomolecules, essential to all known forms of life .
nucleic acid sequence
A succession of letters that indicate the order of nucleotides forming alleles within a or molecule.
The nitrogen-containing biological compounds that form nucleosides, which in turn are components of nucleotides, with all of these monomers constituting the basic building blocks of nucleic acids.
An irregularly shaped region within the cell of a that contains all or most of the genetic material, called the genophore.
The largest structure within the of cells.
An organic compound which serves as the fundamental used in the construction of polymers, such as and , both of which are essential biomolecules within all living organisms.
A collection of joined in a structural unit to serve a common function.
A contiguous living system.
The branch of zoology that concerns the study of birds. Etymologically, the word "ornithology" derives from the ancient Greek ὄρνις ornis ("bird") and λόγος logos ("rationale" or "explanation").
The spontaneous net movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.
The study of the history of life on Earth as reflected in the fossil record. Fossils are the remains or traces of organisms (plants, animals, fungi, bacteria and other single-celled living things) that lived in the geological past and are preserved in the crust of the Earth.
The development of a similar trait in related, but distinct, species descending from the same ancestor, but from different clades.
The study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question, but by their way of life.
The study or practice of pathology with greater emphasis on the biological than on the medical aspects.
A medical specialty that is concerned with the diagnosis of disease based on the laboratory analysis of bodily fluids such as blood and urine, as well as tissues, using the tools of chemistry, clinical microbiology, hematology and molecular pathology.
A numeric scale used to specify the acidity or basicity (alkalinity) of an aqueous solution. It is roughly the negative of the logarithm to base 10 of the concentration, measured in units of moles per liter, of hydrogen ions.
The science of drug action on biological systems. In its entirety, it embraces knowledge of the sources, chemical properties, biological effects and therapeutic uses of drugs.
The composite of an organism's observable features or traits, such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior.
A secreted or excreted chemical factor that triggers a social response in members of the same .
The conducting tissue in plants responsible for the conduction of food particles.
The branch of biology dealing with the functions and activities of living organisms and their parts, including all physical and chemical processes.
The study of phytochemicals, which are chemicals derived from plants.
The science of diagnosing and managing plant diseases.
A substance or treatment of no intended therapeutic value.
The process in which lose water in a hypertonic solution.
The transfer of pollen from a male part of a plant to a female part of a plant, enabling later fertilisation and the production of seeds, most often by an animal or by wind.
A large macromolecule composed of many repeated subunits.
polymerase chain reaction (PCR)
A technique used in molecular biology to amplify a single copy or a few copies of a segment of across several orders of magnitude, generating thousands to millions of copies of a particular sequence.
Having or containing more than two complete sets of .
The study of populations of organisms, especially the regulation of population size, life history traits such as clutch size, and extinction.
A subfield of ecology that deals with the dynamics of species populations and how these populations interact with the environment. It is the study of how the population sizes of species change over time and space. Also called autoecology.
A biological interaction in which a predator kills and eats its prey.
A type of RNA polymerase involved in the replication of .
A short strand of or that serves as a starting point for DNA synthesis.
Any genetic descendant or .
An and progestogen sex which is part of the menstrual cycle, pregnancy, and embryogenesis of humans and other animal species.
An organism which does not have a true .
A polypeptide chain of . It is a body-building nutrient.
A three-dimensional arrangement of atoms in an amino acid-chain molecule.
The application of the principles of biology to the study of physiological, genetic, and developmental mechanisms of behavior in humans and other animals. Also called behavioral neuroscience, biological psychology, and biopsychology.
Giving birth to one of its kind, or .
ribonucleic acid (RNA)
A composed of a series of ribonucleotides which incorporate a set of four nucleobases: (A), (G), (C), and (U). Closely related to , RNA molecules serve in a wide variety of essential biological roles, including , , regulating, and expressing , as well as functioning as signaling molecules.
A complex molecular machine, found within all living , that serves as the site of biological protein synthesis.
A member of a family of enzymes that are essential to life: they are found in all organisms and many viruses.
A type of in which cells have thick lignified secondary walls and often die when mature.
The , enclosed in a protective outer covering, of certain types of .
A type of in which from two parents unite to form the first cell of a new organism.
The degree to which individuals in an population tend to associate in social groups and form cooperative societies.
A field of scientific study that is based on the hypothesis that social behavior has resulted from evolution and attempts to explain and examine social behavior within that context.
The study of microbial and faunal activity and ecology in soil.
The basic unit of classification and a taxonomic rank, as well as a unit of biodiversity, but it has proven difficult to find a satisfactory definition.
The evolutionary process by which populations evolve to become distinct .
The biological cells that can differentiate into other types of cells and can divide to produce more of the same type of stem cells.
A biologically active organic compound with four rings arranged in a specific molecular configuration.
The branch of , , and concerned with the molecular structure of biological , especially and , how they acquire the structures they have, and how alterations in their structures affect their function.
An evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms occurring from symbiosis.
Any close and long-term biological interaction between two different biological organisms, regardless of the nature or degree of the effect on either organism. Examples include mutualism, commensalism, and parasitism.
An interdisciplinary branch of biology and engineering. The subject combines various disciplines from within these domains, such as biotechnology, evolutionary biology, molecular biology, systems biology, biophysics, computer engineering, and genetic engineering.
The scientific study of biodiversity. It is concerned with the discovering and naming of new species of organisms (nomenclature) and arranging these taxa into classification schemes (taxonomy). A large part of modern systematics concerns establishing the evolutionary relationships among various taxa (phylogenetics) using methods of comparative biology (e.g. physiology, behavior, biochemistry, morphology, genetics) and statistical analysis.
A type of lymphocyte that plays a central role in cell-mediated immunity.
A group of one or more populations of an organism or organisms seen by taxonomists to form a unit.
The primary male sex hormone and an anabolic steroid.
One of the four nucleobases in the nucleic acid of that are represented by the letters G–C–A–T.
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA (mRNA) by the enzyme RNA polymerase. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language.
The process in which ribosomes in the cytoplasm or ER synthesize proteins after the process of transcription of to in the cell's nucleus.
The position an organism occupies in a .
Having or consisting of only one , as opposed to being .
One of the four nucleobases in the of that are represented by the letters A, G, C and U.
An organic compound with chemical formula CO(NH2)2.
A liquid byproduct of in humans and in many animals.
A major female hormone-responsive secondary sex organ of the reproductive system in humans and most other mammals.
A membrane-bound organelle which is present in all plant and fungal cells and some protist, animal and bacterial cells.
A valence electron is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair.
The widening of blood vessels.
The type of reproduction in which sexual process is not involved, also known as asexual reproduction.
A small structure within a , or extracellular, consisting of fluid enclosed by a lipid bilayer.
The retention during the process of evolution of genetically determined structures or attributes that have lost some or all of their ancestral function in a given .
The branch of biology that studies
A submicroscopic, infectious, parasitic particle of genetic material contained in a protein coat and which replicates only inside the living cell of a organism.
white blood cell
whole genome sequencing
The process of determining the complete sequence of an organism's genome at a single time.
wobble base pair
A pairing between two nucleotides in molecules that does not follow Watson-Crick base pair rules.
The inner layer of the stems of woody plants, composed of xylem.
The yellow colored photosynthetic pigments.
The plant tissue responsible for the conduction of water from roots to aerial parts of the plant. It forms the woody part of the plant.
The nutrient-bearing portion of the egg whose primary function is to supply food for the development of the .
The branch of biology that studies the animal kingdom, including the structure, embryology, , classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems.
Are heterotrophic (sometimes detritivorous) plankton (cf. phytoplankton). Plankton are organisms drifting in oceans, seas, and bodies of fresh water. Individual zooplankton are usually microscopic, but some (such as jellyfish) are larger and visible to the naked eye.
A diploid reproductive stage in the life cycle of many fungi and protists.
A eukaryotic cell formed by a fertilization event between two gametes.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices.
- Index of biology articles
- Outline of biology
- Glossaries of sub-disciplines and related fields: